Originally Posted by
heidelbergensis
That was all indeed useful! I do like the simplicity of the Tubus Tara, but I find myself needing the additional everyday utility of a rack with a platform in addition to taking panniers.
A good platform front rack that takes mid blade mounts is the Jandd Expedition front rack. It should work well for you in this situation. There used to be a nice Minoura one that would work too - and it came in red to match your paintjob. This bolted together on the top from two halves and provided a sort of "high-low" mounting for panniers. I have one, but I never really liked it. The modern Blackburn "MTF-1" or "bootlegger" platform rack would also work.
Speaking of the other odd feature of the fork, the lower blade threads, I'm a little confused as to how bolt bosses in these two locations would lend itself to mounting a rack. Maybe this set-up was meant for a very specific model of rack?
The lower eyelets and the upper mounts *should* take a standard low-rider, just a little higher up than if it were mounted to the dropout eyelet and a mid-blade mount. The lower eyelets you mention are thus standing-in for the dropout eyelets on a "normal" touring fork. There should be about 6 or 7 inches distance between the lower eyelets and the mid-blade mounts, according to the measures between dropout eyelets and mid-blade eyelets of a couple frames I have here. The distance figure that's thrown around a lot among framebuilders is 165mm. That should work for the majority of front racks, although different framebuilders may put it at different distances to design it to be better for certain racks. This is part of the reason racks come with slotted holes: hopefully by fiddling around you can get the thing pretty much level!
tl;dr: I bet if you measure the distance between the lower eyelets and the mid-blade "DT shifter" mounts, you will find it around 165mm or between 6 and 7 inches, and this will take a standard low rider rack, of which there are at least ten kinds available, C&V or modern.
A Jandd Expedition or modern Blackburn "MTF-1" or "bootlegger" platform rack will likewise mount to these eyelets - although you might need to bend or spread it a little bit to make it work. Or for a more retro option, you could find the Blackburn low rider and a Blackburn platform rack and mount them together, thus foregoing the original hoop that the low-rider came with, because the platform rack's stays provide lateral stiffness in place of the hoop.